In a human body, there are many tubal tissues such as a blood vessel, a bile duct, an ureter and an esophagus, and there is a fear that peculiar disease such as stricture and occlusion is generated. In the case of the blood vessel for example, diseases such as stricture, occlusion, aneurysm and varix is generated in some cases. The aneurysm is such a serious disease that rupture causes major bleeding, and it is necessary to conduct medical treatment swiftly. Therefore, in order to conduct effective medical treatment, various tools have been developed.
Recently, when medical treatment for a stricture portion of a blood vessel or aneurysm is conducted, a metal cylindrical tool called a stent has been used in many cases. For example, when medical treatment is conducted for a stricture portion, the stent is accommodated in a sheath or a catheter (hereinafter, referred to as sheath) and this is transferred to an affected area, and after it reaches the affected area, the stent is separated from the sheath, the stent is increased in diameter by a balloon to enlarge the stricture portion and the stent indwells therein. When medical treatment for aneurysm is conducted, a stent graft in which a stent is covered with artificial blood vessel is allowed to indwell in the aneurysm, and the stent graft is applied against the pressure of blood so that pressure is not applied to the aneurysm.
As the stent, there are provided a mesh stent in which metal mesh cylinder is used, and a loop stent using a cylindrical loop as a whole formed by bending a round rod wire member in a zigzag manner and by joining ends of the wire member as described in Patent Documents 1 and 2.
Especially in the case of the loop stent, there are two cases, i.e., a case in which a loop stent is used alone in correspondence with an affected area where the stent is allowed to indwell, and a case in which a plurality of loop stents are disposed in a longitudinal direction in accordance with a curving state of an affected area, and these loop stents are connected to each other through a wire part called a strut.
A stabilizer hook is mounted on a loop stent located at a top of the stent. The stabilizer hook is utilized when the stent accommodated in a sheath indwells in an affected area. A wire part is disposed in one or some of loop stents constituting the stent. The wire part is used when the stent is inserted into the sheath, or when a position of the stent is adjusted or the stent is pulled back to the sheath when the stent indwells in an affected area.
The loop stent constituting the stent, the stabilizer hook mounted on the top portion, the strut which connects adjacent loop stents with each other, and the pulling-back member are made of metal round rod wire members. Connection parts are formed in connection regions between the loop stent and the stabilizer hook, between the loop stent and the strut, and between the loop stent and the pulling-back member.
The connection part which connects the round rod wire members in the stent is constituted in such a manner that the stent main wire at an object region in the loop stent is formed flat, ends of the strut, the stabilizer hook and the pulling-back member are formed flat, the formed regions are superposed on each other and inserted into a substantially rectangular pipe, and the pipe is caulked as described in Patent Documents 1 and 2.
The stent constituted in the above-described manner is reduced in diameter and inserted into the sheath and sent to an affected area, and when the stent reaches the affected area, the stent is separated from the sheath utilizing stabilizer hook and the stent is increased in diameter by itself or by a balloon. The stent whose diameter is increased in the affected area comes into contact with an inner wall surface of a blood vessel for example, and medical treatment for the blood vessel can be conducted.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-062087
Patent Document 2: Japanese Patent Application Laid-Open No. 2004-097382